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Here are Class 9 Science Chapter 1 Matter in Our Surroundings short and simple notes:

Chapter 1: Matter in Our Surroundings

1. Matter

Anything that has mass and occupies space is called matter.

Example: Air, water, book, table etc.

2. Physical Nature of Matter

Matter is made up of tiny particles.

Particles of matter:

Have space between them

Are continuously moving

Attract each other

3. States of Matter

(1) Solid

Fixed shape and fixed volume

Particles are closely packed

Example: Stone, ice

(2) Liquid

No fixed shape but fixed volume

Particles have more space than solids

Example: Water, milk

(3) Gas

No fixed shape and no fixed volume

Particles are very far from each other

Example: Air, oxygen

4. Change of State

Melting Solid Liquid

Freezing Liquid Solid

Evaporation Liquid Gas

Condensation Gas Liquid

Sublimation Solid Gas (without becoming liquid)

Example: Camphor, naphthalene balls

5. Temperature

Measured in Celsius (C) and Kelvin (K)

0C = 273 K

6. Evaporation

Change of liquid into vapour at any temperature

Faster when:

Temperature is high

Surface area is large

Wind speed is high

Humidity is low

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